According to the prior art, the corks are introduced in bulk into the drum of a vibrating feeder or of a mechanical sorter (called also selector), from which the corks are picked up, oriented, arranged in row and directed to the outlet, where picking up means operate to pick them up one by one and to transfer them to a cork applying station.
The forward movement of the row of corks in the outlet channel, extended horizontally, is caused, in case of vibrating feeders, by the thrust applied by the vibrating action, which is suitably prepared for this purpose, to obtain a component according to a desired horizontal direction.
On the other hand, in case of mechanical sorters, the forward movement of the row is caused by the thrust, applied upstream by the new corks, which are progressively placed at the end of the row.
Obviously, said vibrating feeders and mechanical sorters are dimensioned in such a way, as to supply a medium number of corks, which is larger than the number required by the picking up means.
However, this does not always assure regular feeding of corks to the picking up means, because there can occur transitory, casual situations, which cause “empty spaces” in the row of corks at the outlet (vibrating feeders), or the stop of the row (mechanical sorters), which results in the lack of delivery of the cork to said means in the time interval between one picking up and another.
The main reason, which can cause the above mentioned unexpected situations derives from the fact that the corks are oriented in a wanted outlet order by a passive selection, that is only correctly oriented corks are allowed to pass toward the outlet channel, whereas the others are made fall again into the drum and thus reintroduced into the circulation from the beginning.
If, by any circumstance, an anomalous number of corks in a faulty orientation are fed, a feeding lack can occur transitorily, which results in the row discontinuity or the lack of thrust of the row toward the outlet, even if the medium average rate of corks supplied by system remains larger than the necessary demand.
A first system, which tries to resolve the above mentioned problem includes the over-dimensioning of the vibrating feeder or mechanical selector, so that the average number of corks supplied is much higher than the necessary one.
However, not only is there any absolute security of regular feeding, there is also an increase of dimensions of the above mentioned apparatuses, which is not always compatible with the requirements of the machine, to which they are associated.
According to another solution, the compacting and forward movement of the row of corks is helped by one or more jets of compressed air delivered by relative nozzles.
According to a further known solution, the cork outlet channel is associated to a belt conveyor or a similar device.
The above additional means resolve the functional problem, but they are not recommended if the system is aimed at working in a sterile environment.
Actually, in this case it becomes difficult, or even impossible, to maintain the corks sterile, as they are certified when delivered, if they are subjected to jets of non totally sterile air or to contact with the moving means, which can release polluting particles due to friction between them or with the corks.
Known devices for feeding pickup station of filling and plug applying machines, substantially as reported in the preamble of the independent claim, are described in various publications such as U.S. Pat. No. 3,859,973, GB-B-1 035 549, GB-B-1 061 705, U.S. Pat. Nos. 3,975,886, 3,710,924, 2,826,885, 4,995,781, 5,115,617, 6,115,992 and 6,430,896.
All the above mentioned publications reports about a feeding channel supplying corks by gravity to a cork applying machine.